Pollutant removal from air in closed spaces

ABSTRACT

A catalyst system useful at room temperature for the destruction of ozone (O 3 ), which is comprised of a washcoat of high surface area support containing Mn/Cu catalyst deposited on a macroporous carrier, such as a honeycomb monolith, optionally with the addition of noble metal (such as Pt) washcoat to remove carbon monoxide.

This app is a div. of Ser. No. 08/687,059 filed on Aug. 7, 1996 now U.S.Pat. No. 5,686,924.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a catalyst, catalyst system andapparatus to purify air in closed spaces such as rooms, vehicles, officebuildings, and the like and in particular to a catalyst for ozoneremediation at "room temperature".

2. Description of Related Art

Air purifiers for use in homes, sick rooms, offices and closedatmosphere buildings are known. These purifiers remove odors and in somecases introduce ozone or other material to oxidize impurities in theair. U.S. Pat. No. 5,422,331 discloses a catalytic metal oxide depositedover an undercoat of a mixture of a fine particulate metal oxide and asolution for removing ozone in air plane cabins or other closed areas.U.S. Pat. No. 4,405,507 discloses a precious metal ozone decompositioncatalyst containing a platinum Group metal and a Group VIII metal oxidein closed spaces.

The present invention provides a catalyst and a system and method usingthe catalyst for the remediation of atmospheric ozone and/or carbonmonoxide at "room temperature". It is a particular advantage that thepresent catalyst and the system may be used with existing particulateair filtration equipment. It is a feature of the present invention thatit may also be adapted to remove CO from air concurrently with the ozoneremoval.

SUMMARY OF THE INVENTION

Basically the present invention is a catalyst component and a catalystsystem comprising a carrier having the catalyst component depositedthereon useful for the reduction of ozone in air, the process of makingthe catalyst components and the catalyst system and the process of usingthe catalyst system to remediate air. The catalyst component comprises acombination of a manganese component and a copper component applied to ahigh surface area support and the catalyst system comprises the catalystcomponent applied to a carrier. The manganese and copper components areusually present as oxides or hydroxides in use, e.g MnO₂, Cu(OH)₂ andCuO. The manganese component comprises 2 to 50 weight % of the catalystcomponent and the copper component comprises 1 to 40 weight of thecatalyst component, preferably 5 to 25 wt. % manganese as MnO₂ and 2.5to 15 wt.% copper as Cu(OH)₂. The catalyst component comprises 5 to 20wt. % of the total weight of the carrier and catalyst component.

In addition to the ozone reduction components other components may beadded to the catalyst to remove CO, NO_(X), and the like. A noble metalcomponent comprising a noble metal applied on a high surface areasupport and applied on the carrier may be added to remove CO. Thepreferred noble metal is a platinum. The noble metal may comprise fromabout 0 to 20 wt. % of the catalyst component measured as the metal. Acatalyst system containing both the Mn/Cu component and the noble metalpreferably is coated with an absorber. It is believed that the absorberfrees the noble metal component molecules from the CO reaction productsby absorbing the reaction products away from the noble metal component.The noble metal component comprises 0.1 to 5.0 wt. % of the total weightof the carrier and added components (catalyst component and noble metalcomponent and any others).

A separate apparatus from an existing filtering system may be used whichcomprises a catalyst component, means to move air over the catalystcomponent and preferably a heater to control the air temperature. Thecatalyst component can be mounted in a canister or mounted integrallywith a space heater and/or air conditioner.

The term "room temperature" is used herein to include temperatures inthe range of 50-120° F. The ozone may be present in only trace amounts,i.e. 50 to 1000 ppb, which is in general the operating range for whichthe present catalyst system is designed. Carbon monoxide is also presentin trace amounts, e.g. 0.1 to 100 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing % of ozone destruction for a 0.78 g./in³ Mn/Cucatalyst component on a 400 cpsi honeycomb (monolith)--500 ppb ozone at75° F.

FIG. 2 is a graph comparing various honeycomb cell sizes with Mn/Cucatalyst composition for % ozone destruction 500 ppb ozone at 75° F.

FIG. 3 is a graph comparing 0% relative humidity and 69% relativehumidity for % ozone destruction--500 ppb ozone at 75° F., 400 cpsi.

FIG. 4 is a graph comparing MnO₂ loading to % ozone destruction--500 ppbozone at 75° F., 400 cpsi, 69% RH.

FIG. 5 is a graph comparing % CO destruction at various levels ofabsorber over Mn/Cu (50%) Pt (50%) deposited on 400 cpsicarrier--265,000 hr⁻¹ vapor hourly space velocity (VHSV), 10 ppm CO, 500ppb ozone, 0% RH at 75° F.

FIG. 6 is a graph comparing CO and ozone destruction at various levelsof Mn/Cu and Pt deposited on 400 cpsi carrier with 1% K₂ CO₃absorber--300,000 hr⁻¹ vapor hourly space velocity (VHSV), 10 ppm CO,500 ppb ozone at 75° F.

FIG. 7 is a graph comparing the effect firing the Mn/Cu coated carrieron ozone destruction--400 cpsi carrier with 1.91 g./in³ Mn/Cu, 500 ppbozone at 75° F.

FIG. 8 is a graph showing the effect of VHSV on ozone destruction for1.91 g./in³ Mn/Cu deposited on 400 cpsi carrier--500 ppb ozone at 75° F.

FIG. 9 is a graph showing the performance of only Pt catalyst on CO andO₃ removal at various VHSV--400 cpsi monolith, 1.3g/in³ alumina, 46g/ft³ Pt, 400 ppb O₃ , 10ppm CO, 69% RH at 75° F.

FIG. 10 is a graph showing the performance of only Pt catalyst on O₃ atdifferent levels of CO--400 cpsi monolith, 1.3 g/in³ alumina, 46 g/ft³Pt, 500 ppb O₃, 69% RH at 75° F.

FIG. 11 is a schematic cross sectional elevational view of a filtersystem using the present catalyst system.

DETAILED DESCRIPTION

The catalyst system herein described is especially useful at roomtemperature in commercially available room air cleaners for thedestruction of ozone (O₃). With the addition of noble metal e.g., as awashcoat to the base metal washcoat (Mn/Cu), carbon monoxide is alsodestroyed but at a slower rate. The preferred noble metal is platinum.The equations for the oxidation of ozone to oxygen and carbon monoxideto carbon dioxide are:

    20.sub.3 →>30.sub.2

    2CO+O.sub.2 →>2CO.sub.2

The base metal washcoat may be prepared by applying a solution of cupricnitrate (Cu(NO₃)₂) and potassium permanganate (KMnO₄) to high surfacearea alumina powder by the method of incipient wetness. The copper andmanganese compounds can be reduced and/or precipitated with a solutionof a carbohydrate such as sucrose. The powder is washed to removepotassium hydroxide and then milled with dilute acetic acid into a highsurface area catalytically active washcoat. The copper component andmanganese component may be applied to the carrier in any order, howeverconcurrent deposition is preferred.

The noble metal washcoat may be prepared by applying a solution of anaqueous platinum salt to high surface area alumina powder by the methodof incipient wetness. The powder is fired at 500° C. to volatilizecontaminants such as organic residuals and interstitial water. Thepowder is then milled with dilute acetic acid into a high surface areacatalytically active washcoat. The noble metal washcoat can also be madeby applying the aqueous Pt(OH)₆ solution to the catalyst system afterthe alumina washcoat has been deposited on the support structure. Thenoble metal washcoat may be applied in order to the carrier, although itis preferred to deposit it concurrently with the Cu/Mn components.

The high surface area support is made of alumina, zirconia, titania,silica or a combination of two or more of these oxides. Preferably, thehigh surface area support is made of alumina. The surface area of thesupport is in the range of 50 to 350 square meters per gram, preferably100 to 325 square meters per gram, and more preferably 100 to 200 squaremeters per gram.

The composition of the ceramic carrier can be any oxide or combinationof oxides. Suitable oxide supports include the oxides of Al (α--Al₂ O₃),Zr, Ca, Mg, Hf, and Ti.

The structure and composition of the carrier is of great importance..The carrier structure affects the flow patterns through the catalystsystem which in turn affects the transport to and from the catalystsurface and thus the effectiveness of the catalyst. The carrier shouldbe macroporous with 100 to 600 pores per square inch (30 to 80 pores perlinear inch). The pores should yield a tortuous path for the reactantsand products such as is found in foam ceramics (generally understood toinclude honeycomb structures). Straight channel extruded ceramic ormetal monoliths yield suitable flow dynamics only if the pore size isvery small with greater than 14 pores per linear inch.

Ceramic honeycomb is the preferred catalyst carrier because it is a highsurface area material that is easy to coat, it has a low pressure dropin the air stream of the room air cleaner and it is available in avariety of cell counts per square inch. The honeycomb is preferably madefrom cordierite and is coated with the catalytically active washcoat andplaced inside a room air cleaner. It is preferably placed in the airintake after all filters or after the electrostatic precipitator. Thecatalyst removes ozone from the air in the room by oxidation to oxygen.

The catalyst system may be in a shape such as a sphere, solid cylinder,hollow cylinder or sheet.

The catalyst system incorporating a noble metal for CO removalpreferably is coated with at least one alkali or alkaline earthcompound, which can be hydroxide compound, bicarbonate compound, orcarbonate compound, or mixtures of hydroxides and/or bicarbonates and/orcarbonated compounds. Preferably, the absorber comprises substantiallyall carbonate, and most preferably sodium carbonate, potassium carbonateor calcium carbonate. The absorber is disposed on the material at aconcentration in the range of 0.5 to 20 percent by weight of thematerial, preferably 5.0 to 15 percent by weight of the material, andmost preferably about 10% percent by weight of the material.

Ozone may be created by high voltage discharges, e.g. lightening andhigh voltage electronic circuitry, which is present in copying andfacsimile machines and cathode ray tubes used in computer and televisionsets. The present ozone catalyst system may be placed inside theelectronic equipment that actually creates ozone. Other applicationswould include places where this equipment is used such as offices,mailrooms, copying rooms, schools, hospitals, nurseries and day carecenters, private homes, toll booths submarines, cars, buses or anyclosed in space where ozone may originate or buildup.

The design of the apparatus to present polluted air to the CO and O₃destruction system should contain a high efficiency filter to removeparticulates. Since the catalyst operates at such a low temperature, thecatalyst surface is susceptible to fouling by dust which tends to clingto the catalytic surface area. Since such particulates can be anirritant to the respiratory system their removal is an added benefit.

These catalysts can operate in a fashion to achieve very highdestruction efficiencies in a single pass. Such a design would use arelatively large amount of catalyst and can be expensive. In order tomake a cost effective destruction system, smaller amounts of catalystcan be used with subsequent lower conversion per pass but which canachieve overall high efficiency destruction by recirculating the roomair. The minimum single pass destruction efficiency is determined by thesize of the fan or blower required to move the air and the room size.For example, if the fan is rated at 250 standard cubic foot per minutethen the air in a 1000 cubic foot room is recirculated 15 times in anhour. In this case 99.5% of the room pollutants would be destroyed inone hour even if the conversion per pass was only 30%. If the roomvolume were to be 2044 cubic feet the same recirculating air cleanerwould have only 7 turnovers per hour and the single pass efficiencywould need to be 55% to achieve 99.5% destruction efficiency. The singlepass efficiency is determined by the volume of the catalyst employed.

FIG. 11 shows a closed container 10 having the catalyst systemcontaining at least one of the catalyst components (Mn/Cu, noble metalor mixture) supported on a porous carrier 16. The air flow is shown bythe arrows from entry 6 to exit 8. Preferably there are one or morefilters upstream of the catalyst system. In this embodiment an HEPAfilter 14 is preferably immediately upstream and a second, lessefficient filter 12 upstream before the other two components.

EXAMPLE 1

A. Catalyst Preparation

Washcoat preparation

1. Raw Materials

a. Deionized Water

b. Potassium Permanganate

c. Cupric Nitrate--technical grade; Baker-Mallinckrodt

d. Alumina, Puralox SCF a-160 -Condea Chemie GmbH (Brunsbuttel, Germany)

e. Glacial Acetic Acid--99.5% pure technical grade

f. Octanol

g. Sucrose --food grade

h. Pt(OH)₆ aqueous solution--Advanced Catalyst Systems (Knoxville,Tenn.)

2. Washcoat Procedure

a. Mn/Cu Catalyst (GLBM) Washcoat

A given weight of Puralox SCF a-160 alumina powder is wetted to thepoint of incipient wetness (50% of the dry weight of the powder) with asolution of 19.5 wt% KMnO₄ and 4.6 wt% Cu(No₃)₂ 5H₂ O. After drying at125° C., the powder is again saturated to the point of incipient wetnesswith a solution of 10.0% sucrose which reduces the KMnO₄ to MnO₂ andprecipitates Cu(OH)₂ when heated to 125° C. The procedure is repeated 2times more with the same concentration and weight of KMnO₄ andCu(NO₃)5H₂ O solution and heated at 125° C. The powder is now 13.0% MnO₂and 7.5% CU(OH)₂. The dry washcoat powder after preparation is 13.0%manganese dioxide (MnO₂) and 6.1% cupric oxide (CuO) on Puralox SCFa-160 alumina powder.

One of the byproducts of the reduction of KMnO₄ to MnO₂ is KOH. Thepowder is washed with 0.5% acetic acid to neutralize the KOH and rinsedwith deionized H₂ O to remove KC₂ H₃ O₂ and any other solublebyproducts. The powder is filtered with medium filter paper to remove asmuch water as possible and then dried at 125° C. The powder is thenmilled in a ceramic roller mill one-half full of ceramic milling mediawith an equal weight plus 10% of 7% acetic acid and a small amount of adefoaming agent, such as octanol, for 8-12 hours at 32 RPM. Theresulting suspension has a specific gravity of 1.40, a pH of 4.4 to 4.8and is approximately 42% solids, which is designated as GLBM catalystwashcoat.

b. Pt Catalyst (GLPM) Washcoat

The GLPM catalyst washcoat is prepared by wetting a given weight ofPuralox SCF 1-160 with 5.3% aqueous Pt(OH)₆ solution to the point ofincipient wetness. The powder is dried at 125° C and fired at 500° C. tovolatilize contaminants and activate the Pt. At this point, the powderis 2.6% Pt.

The powder is then milled in a ceramic roller mill one-half full ofceramic milling media with an equal weight of 7% acetic acid and a smallamount of octanol for 12 hours at 32 RPM. The resulting suspension has aspecific gravity of 1.46, a pH of 4.3 and is approximately 50% solids,which is designated as GLPM catalyst washcoat.

c. Preparation of catalyst system

For the remediation of both ozone and carbon monoxide, the GLBM and GLPMwashcoats are proportionally mixed together by weight and rolled on aroller mill for 1 hour at 32 RPM.

The ceramic honeycomb carrier is Ceclor brand made by Corning (Corning,N.Y.). It is a high surface area material made of cordierite which ismagnesium aluminum silicate. The carrier is dipped in the washcoatslowly and allowed to soak for 45 seconds, after which the cells areblown with compressed air to clear them. Approximately 25% of thesuspension by weight of the block is used to coat each block. The coatedblocks are dried at 125° C. and can be calcined at 300° C. to drive offwater and other volatile agents.

B. Test Method

The method used to test the performance of the catalyst system uses aDasibi 1009-MC Calibration System with ozone generator and a Dasibi1003-AH ozone analyzer to test for ozone destruction. Carbon monoxidedestruction is tested by diluting a compressed gas mixture (0.2% Co innitrogen) with the Dasibi 1009-MC and analyzing with a ThermoEnvironmental 48H CO analyzer. The catalyst reactor and all tubing aremade of teflon to reduce ozone degradation by the background system. Thesample is wrapped with teflon tape to prevent gas bypass and placedinside the teflon reactor. The sample is then exposed to 400 ppb or 100ppb O₃ and/or 10 ppm CO and % O₃ and % CO destruction calculated. Thesample is tested at different flow rates and vapor hourly space velocity(flow rate/hr/volume catalyst, abbreviated VHSV) is calculated.

C. Evaluations

1. FIG. 1 shows the effect of VHSV on ozone destruction of GLBM catalystsystem. As VHSV increases, linear velocity increases, the amount of gasprocessed increases and the amount of ozone destroyed by the catalystsystem decreases. In other words, the catalyst system becomes lesseffective when the amount of gas that flows through it increases. Asflow increases through the catalyst system, the molecules of gas have ashorter residence time, which is the time it takes a molecule to travelthrough the catalyst system. The target space velocity for a room aircleaner is 300,000 hr⁻¹. This balances the cost of the catalyst systemwith the efficiency of destruction of ozone. The same catalyst systemsample was tested for % CO destruction with 10 ppm CO at roomtemperature. There was no appreciable destruction of CO.

2. Honeycomb blocks with cell counts of 200, 400 and 600 per square inch(cpsi) with GLBM catalyst component were tested for % ozone destruction.FIG. 2 shows that ozone destruction is greatest for 600 cell, and leastfor 200 cell. The higher cell count provides more surface area forcontact with ozone molecules and therefore gives higher ozonedestruction efficiency.

400 cpsi honeycomb is presently used for testing purposes because it isreadily available in square blocks that can be easily modified to fitthe filter area of a room air cleaner. (The 600 cpsi honeycomb iscurrently available only in a circular shape that will not fit readilyinto a room air cleaner.) The % ozone destruction of 400 cpsi honeycombcoated with GLBM ozone destruction catalyst is 82% at 300,000 hr⁻¹ spacevelocity.

3. The above evaluations were obtained under dry conditions usingcompressed air from a tank. To simulate the relative humidity (RH) of aroom (50-80% RH), the dry air was bubbled through deionized water beforeit went into the test reactor. This gave a RH of approximately 69%,which is a comfortable level that can be expected indoors during thesummer when most pollution levels outdoors go up. FIG. 3 shows the GLBMcatalyst effectiveness under dry conditions compared to 69% RH. It wasfound that relative humidity has a negative effect on the ability of theGLBM catalyst to destroy ozone, 85% effective at 0% RH versus 59%effective at 69% RH, tested at a space velocity of 300,000 hr⁻¹.

4. In this evaluation, alumina powder was prepared with one impregnationof KMnO₄ and Cu(NO₃)₂ 5H₂ O only, reduced, dried and washed, and thenprepared into a washcoat. It was 5.1% MnO₂ and 1.6% CuO. The testresults were compared to test results from a washcoat with 13% MnO₂ and3% CuO, shown in FIG. 4. The 4.1% MnO₂ washcoat was 52.5% effective atdestroying ozone compared to 61.5% for the 13% MnO₂ washcoat, bothtested at a space velocity of 300,000 hr⁻¹.

5. The GLBM catalyst was tested for ability to destroy carbon monoxide(CO) at 75° F. with 0% RH. It was found that the GLBM catalyst destroyedalmost no CO under dry or humid conditions. Noble metal (GLPM) catalyston alumina powder was added in the proportion 50% GLBM, 50% GLPM. FIG. 5shows that under dry conditions, at a space velocity of 265,000 hr⁻¹,with 500 ppb ozone and 10 ppm CO, a mixture of 50% GLBM and 50% GLPMdestroyed 88.76% ozone and 9.52% CO.

To improve the CO destruction efficiency, an absorber was coated overthe washcoat. It was found that % CO destruction was increased from9.52% with no absorber to 42.48% with absorber. A solution of 1% K₂ CO₃was used to coat the catalyst piece. Solutions of 5% and 10% K₂ CO₃ werealso used to coat pieces and were expected to give better % COdestruction efficiencies than 1% K₂ CO₃. The results in FIG. 5 show thatthey did not. The most effective was 1% K₂ CO₃. The higher percentagesof K₂ CO₃ may have masked the catalyst causing a reduction in % COefficiency. The presence of K₂ CO₃ did not have significant effect on %O₃ destruction. Percent O₃ destruction was reduced from 88.75% to 85.83%with 1% K₂ CO₃, to 82.22% with 5% K₂ CO₃, and to 84.62% with 10% K₂ CO₃.

The percentage of GLPM in the washcoat was also varied. The results aregiven in FIG. 6. 50% GLPM, 50% GLBM gave the best results for % COdestruction.

6. The 50% GLBM, 50% GLPM with 1% K₂ CO₃ sample previously tested for %CO destruction was tested again both dry and with 69% RH. The % COdestruction result under dry conditions was much less than whenpreviously tested--3.63% vs. 42.48% at the earlier date. A sample withthe same loading of the same washcoat was also retested at 261,000 hr⁻¹space velocity and found to destroy only 8.62% of the CO present. Thissample was then washed with 0.5% acetic acid, rinsed with deionizedwater, fired for 15 min. at 300° C. and recoated with 1% K₂ CO₃. Thesample then destroyed 50.5% of the CO under dry conditions at 326,000hr⁻¹ space velocity. Washing and firing the sample at 300° C. broughtback the previous level of % CO destruction. This sample was tested with69% RH and the % CO destruction decreased to 4.0%. Water vapor has adramatic negative effect on the efficiency of the GLBM/GLPM catalyst.

7. The effect of firing the honeycomb after it is washcoated was testedby cutting 2 samples from the same 400 cpsi block washcoated with 1.91g/in³ GLBM catalyst (13% MnO₂, 3% CuO). The block had been dried at 125°C. One sample was tested unfired and the other was fired at 300° C. for15 minutes. Firing the sample removes interstitial water, acetic acidand other volatile compounds. The samples were tested dry and with 69%RH with 500 ppb ozone at 75° F. FIG. 7 shows that the fired sampletested dry gave 84% O₃ destruction at 300,000 hr-¹ VHSV. The unfiredsample, tested dry was 81% O₃ destruction at 300,000 hr⁻¹ VHSV. Whentested with 69% RH, the trend reverses and the unfired sample is betterthan the fired sample, 61% versus 59% O₃ destruction at 300,000 hr-¹.

EXAMPLE 2

230 g of GLBM washcoat was made by applying 12.5 g KMnO₄ and 9.5gCu(NO₃)₂ 3H₂ O in 50 g deionized water to 100 g Puralox SCF a-160alumina powder by the method of incipient wetness. The powder was driedat 125 ° C., treated with 50 g of 10 % sucrose and dried at 125 ° C.again. Another 12.5 g KMnO₄ and 9.5 g Cu(NO₃)₂ 3H₂ O in 50 g deionizedwater was applied, the powder dried at 125 ° C.. The powder was milledin a ceramic mill with 100 g 7% acetic acid for 8 hours. 75 g of 7%acetic acid was added to recover and dilute the washcoat to a specificgravity of 1.32. The pH was 4.16. The dried coating was 13% MnO₂ and6.1% CuO. A sample was made by dipping a preweighed 400 cpsi piece inthis washcoat. The excess was blown off with compressed air and thesample was dried at 125° C.. The sample was reweighed and the washcoatloading was 1.19 g/in³. The results of the ozone destruction test aregiven in FIG. 1.

EXAMPLE 3

204 g of GLBM washcoat was made by applying 15.0 g KMnO₄ and 4.95 gCu(NO₃)₂ 3H₂ O in 50 g deionized water to 100 g Puralox SCF a-160alumina powder by the method of incipient wetness. The powder was driedat 125° C., and reduced in the oven while being heated overnight.Treatment with sucrose was not necessary. Another 15.0 g KMnO₄ and 4.95g Cu(NO₃)₂ 3H₂ O in 50 g deionized water was applied, and the powderdried at 125° C.. The powder was treated to the point of incipientwetness with 15 g of formic acid diluted to 50 g with deionized water.After drying at 125° C., the powder was washed 1 time with 1% aceticacid, rinsed 2 times with deionized water and dried at 125° C. again.The powder was milled in a ceramic mill with 124 g of 7% acetic acid for8 hours. 40 g of 7% acetic acid were added to recover and dilute thewashcoat to a specific gravity of 1.38. The pH was 4.65. The driedcoating was 13.0% MnO₂ and 3.0% CuO. A sample was made by dipping apreweighed 400 cpsi piece in this washcoat. The excess was blown offwith compressed air and the sample was dried at 125° C.. The sample wasreweighed and the washcoat loading was 1.19 g/in³. The results of theozone destruction test are given in FIG. 8.

EXAMPLE 4

In an effort to increase CO destruction, a sample was made with aluminawashcoat without the precious metal component added. A 400 cpsi piecewas dipped in this washcoat (1.3 g/in³), the channels blown clear withcompressed air, and the piece fired at 500° C. for 30 minutes. Thesample was dipped in a 1.94% Pt(OH)₆ solution, dried at 125° C. for 10minutes and fired at 500° C for 10 minutes. This gave a Pt loading of 46g/ft³. The sample was tested without an absorber coating. FIG. 9 showsthat firing at 500° C. greatly improves the GLPM catalyst's ability tooxidize CO. FIG. 10 shows that increasing the CO concentration givesslightly improved ozone destruction and that CO destruction is notsignificantly affected.

EXAMPLE 5

A coating was made by mixing log of GLBM coating from Example 1 with 15g of washcoat suspension made as GLPM washcoat but without the preciousmetal component added. This gave a mixture that was 40% GLBM coating. A400 cpsi piece was coated with the mixture, the channels cleared withcompressed air, and the piece fired at 500° C. for 30 minutes. The piecewas dipped in a 1.9% Pt(OH)₆ solution for 5 seconds and the channelsagain cleared with compressed air. The piece was dried for 10 minutes at125° C and fired at 500° C for 30 minutes. This gave a Pt loading of 46g/ft³. The piece was tested without an absorber coating. The piece wastested with 500 ppb ozone and 10 ppm CO. At a space velocity of 161,000hr⁻¹ and 54% RH, O₃ destruction was 93.77% and CO destruction was45.37%. At a space velocity of 229,000 hr⁻¹ and 54% RH, O₃ destructionwas 90.20% and CO destruction was 41.67%. Increasing relative humidityto 60% at 229,000 hr⁻¹, O₃ destruction was 84.06% and CO destruction was30.00%. Increasing the CO concentration to 20 ppm at these conditionsdid not change the CO or O₃ destruction.

The invention claimed is:
 1. An air purifier consisting of a container,blower to move air through a high efficiency particulate removal device,upstream of a catalyst system comprising a catalyst component consistingof a combination of a manganese component, a copper component and anoble metal component applied to a high surface area support saidcatalyst component being applied to carrier.
 2. An air purifieraccording to claim 1 wherein the air is recirculated through saidcatalyst system at least 2 times per hour.
 3. The air purifier accordingto claim 1 in which the high efficiency particulate removal deviceremoves at least 95% of all particulates greater than 0.3 microns. 4.The air purifier according to claim 1 comprises a high efficiency airfilter.
 5. The air purifier according to claim 1 comprises anelectrostatic precipitator.
 6. The air purifier according to claim 1wherein said manganese component comprises 2 to 50 weight % of thecatalyst component.
 7. The air purifier according to claim 1 whereinsaid copper component comprises 1 to 40 weight % of the catalystcomponent.
 8. The air purifier according to claim 1 wherein saidmanganese component comprises 2 to 50 weight % of the catalystcomponent, said copper component comprises 24 to 40 weight % of thecatalyst component and said noble metal comprises from 0.1 to 20 wt. %of the catalyst component measured as the metal.
 9. The air purifieraccording to claim 1 wherein the catalyst component comprises 5 to 20wt. % of the total weight of the carrier and catalyst component.
 10. Theair purifier according to claim 1 wherein the manganese and coppercomponents are present as oxides or hydroxides.
 11. The air purifieraccording to claim 1 wherein said carrier comprises macroporous ceramicor metal foam.
 12. The air purifier according to claim 1 wherein saidcarrier comprises macroporous ceramic monolith.
 13. The air purifieraccording to claim 1 wherein said carrier comprises macroporoushoneycomb cordierite.
 14. The air purifier according to claim 1 whereinsaid high surface area support comprises alumina.
 15. The air purifieraccording to claim 11 wherein said manganese component and coppercomponent are incorporated with the high surface area support and saidsupport is coated on to said carrier and said noble metal componentcoated thereon.
 16. The air purifier according to claim 15 wherein saidmanganese component comprises 2 to 50 weight % of the catalyst componentand said copper component comprises 1 to 40 weight % of the catalystcomponent.
 17. The air purifier according to claim 16 wherein thecatalyst component comprises 5 to 20 wt. % of the total weight of thecarrier and catalyst component.
 18. The air purifier according to claim17 wherein said carrier comprises macroporous ceramic monolith.
 19. Theair purifier according to claim 18 wherein said high surface areasupport comprises alumina.
 20. The air purifier according to claim 19wherein said carrier comprises cordierite.
 21. The air purifieraccording to claim 1 wherein said noble metal is platinum.
 22. The airpurifier according to claim 1 wherein said noble metal comprises from0.1 to 20 wt. % of the catalyst component measured as the metal, saidnoble metal component comprising 0.1 to 5.0 wt. % of the total weight ofthe carrier and added components.
 23. The air purifier according toclaim 1 said catalyst system is coated with an absorber.